VOLCANIC PHENOMENA. 355 



and the Cordilleras of the New World, and to furnish data CHAPTEK. 

 from whence to deduce some of the laws wiiicli govern ^^^^VIIL 

 the most remarkable phenomena of the globe. In fol- 

 lowing out the great plan which he had set himself, 

 Baron Humboldt has devoted the two first volumes of 

 his work to an elaborate treatise on the peculiar phe- 

 nomena attendant on the upheaval of continents, and the 

 remarkable geological changes which liave produced the Geological 

 great mountain chains, and the other striking physical '^'"*"S'* 

 conformations of the earth's crust. His Memoir on the 

 Mountain Chains and the Volcanoes of Central Asia 

 possesses very great attractions to the student of science, 

 though much of the work, and the mode of treating the 

 very comprehensive subjects which it includes, renders it 

 too strictly scientific to offer the attractions which Hum- 

 boldt's personal narrative possesses for the general reader. 

 The following abstract will afford some idea of the earlier 

 portion of this valuable work. 



In our present state of knowledge, volcanic phenomena Volcanic 

 are not to be considered as relating peculiarly to the ^' 

 science of geology, but rather as a department of general 

 physics. When in action they appear to result from a 

 permanent communication between the interior of the 

 globe, which is in a state of fusion, and the atmosphere 

 which envelopes the hardened and oxidated crust of our 

 planet. Masses of lava issue like intermittent springs ; 

 and the superposition of their layers which takes place 

 under our eyes bears a resemblance, on a small scale, to 

 the formation of the ancient crystalline rocks. On the 

 crest of the Cordilleras of the New World, as well as in Uniformity 

 the south of Europe and the western parts of Asia, an in- " "^^" '*" 

 timate connexion is manifestly traceable between the 

 chemical action of volcanoes properly so called, or those 

 which produce rocks, — their form and position permitting 

 the escape of earthy substances in a state of fusion, — 

 and the mud-volcanoes of South America, Italy, and the Mud 

 Caspian Sea, which at one period eject fragments of rock, vo''^""""- 

 flames, and acid vapours, and at another vomit muddy 



